Do you leave beer at parties or dinners as a courtesy?

General rule is if the box is half empty then you leave the wine for the host.

Yes

I usually bring my beer in an ice chest, so no. I don't empty out my ice chest before leaving a party. However, if I just bring a sixer or twelve pack and stick it in their fridge, then I'll typically leave whatever is left, which usually isn't much because I like to party.

most of the parties I go to the host either has a fully stocked bar for their guests or has someone catering a bar.

Good question. I always do unless they insist I take it. We had some friends come for a crawfish boil years ago. They came in put about 10 beers in the fridge. When they left they gathered up the 2 or 3 that were left and took with them. I thought a lot more highly of them until they did that.

Depends on the beer. Cheap light beer I'll leave, expensive craft beer I'm taking.

I usually leave 5-6 half finished beers scattered around the house.

Yes, but I don't do it as a courtesy to the host........ I do it because I'm lazy.

All I know is when I have a dinner party at my place or have a crawfish/crab boil and invite people over I always make sure my bar is stocked and beer fridge is full. Obviously if people want their craft beer or fancy wine they bring their own.

I usually bring a 2 liter of Pepsi like George Costanza. Whatever is leftover goes home with me.